Secondary spontaneous thrombosis of a giant aneurysm located distally on a feeding artery after embolization of an associated arteriovenous malformation

Unruptured Aneurysmal Shrinkage of the Distal Posterior Inferior Cerebellar Artery Following Stent Jailing of the Arterial Orifice: A Case Report

A 57-year-old woman who presented with a sudden severe headache and subsequently diagnosed with a subarachnoid hemorrhage was referred to our hospital. CTA revealed a large irregularly shaped dissecting aneurysm of the right vertebral artery (VA) and a small round distal aneurysm of the right posterior inferior cerebellar artery (PICA), which originated just proximal to the VA aneurysm. We diagnosed the VA aneurysm as a ruptured aneurysm and performed endovascular treatment the day the patient was hospitalized. Because the left VA was aplastic, stent-assisted coiling was performed to preserve the blood flow of the right VA, following the administration of antiplatelets and heparin. The proximal part of the laser-cut closed-cell stent jailed the orifice of the right PICA. The postoperative course was uneventful, and she was discharged from the hospital 3 weeks later without any neurological deficits. The follow-up VA angiogram revealed complete disappearance of the distal PICA aneurysm 17 months after stent jailing. Flow reduction by stent jailing of the arterial orifice is considered to be the main mechanism of aneurysmal shrinkage. Jailing of the orifice of the cerebral artery using even a low-metal-coverage stent may cause arterial flow reduction, which may shrink a distal aneurysm.

Complete spontaneous thrombosis in unruptured non-giant intracranial aneurysms: A case report and systematic review

BACKGROUND AND AIM

Spontaneous partial or complete thrombosis of saccular unruptured intracranial aneurysm (UIAs) is a known occurrence in giant aneurysms. However, spontaneous complete thrombosis of non-giant aneurysms is a rare event in the natural history of UIAs. The aim of this paper is to report on the cases from literature of complete spontaneous thrombosis with a view to identify possible factors associated with this phenomenon.

MATERIAL AND METHODS

We performed a systematic review of the current literature on spontaneous complete thrombosis of saccular, non-giant, unruptured UIAs, including a case that we treated at our institution. We analysed the possible risk factors for thrombosis, association with ischemic events, rupture and recanalization. We reviewed the possible management's strategies for this group of patients described in literature to date.

RESULTS

We identified 26 patients for a total of 27 thrombosed aneurysms from the literature review (including our case). Thrombosis was prevalent in women, in the anterior circulation and in larger aneurysms. Endovascular events in the parent artery, either spontaneous or iatrogenic, were associated with spontaneous thrombosis in 4 cases. In 47 % of cases an antiplatelet treatment (AP) was introduced. Rupture and recanalization of the aneurysm were observed in 14 % and 33 % respectively. A larger size was the only factor statistically associated with rupture (P = 0041). AP was not statistically associated with recanalization or rupture of the aneurysm.

CONCLUSION

Complete spontaneous thrombosis is not a curative event. Its natural history is associated with recanalization, rupture and ischemic stroke. Conservative treatment with a clinical-radiological follow up and treatment with AP is a safe option for small aneurysms. Definitive aneurysmal exclusion should be considered in medium and large aneurysms due to the significant risks associated with untreated aneurysms.